豚鼠耳颞部^(60)Coγ射线照射对耳蜗核影响的实验研究

An Experimental Study on the Effect of ^(60)Co γ Rays Irradiation on Guinea Pig Cochlear Nucleus

目的探讨60 Coγ射线照射对豚鼠耳蜗核神经元的影响。方法 48只豚鼠随机分为对照组(8只)和实验组(40只),实验组豚鼠于右耳颞部做一次性40Gy 60 Coγ射线照射后的1、4、7、14、30d行听性脑干反应(audi-tory brainstem response,ABR)测试,然后处死,行耳蜗核石蜡切片HE染色及免疫组织化学染色,观察细胞形态及半胱氨酸天冬氨酸蛋白酶3(Caspase 3)。对照组不予60 Coγ射线照射,行ABR测试后行耳蜗核HE染色,方法同实验组。结果对照组ABR反应阈为29.17±1.95dB SPL,实验组在接受60 Coγ射线照射后1、4、7、14、30dABR阈值升高,分别为31.88±2.59、35.00±3.17、35.83±2.04、39.17±2.05、41.67±2.58dB SPL,照射后4、7、14、30d ABR反应阈与对照组比较差异有统计学意义(P<0.05);实验组各时间点ABR波I、II、III潜伏期及I-II、II-III、I-III波间期延长,与对照组比较差异有统计学意义(P<0.05)。HE染色显示实验组在照射后不同时间点均出现耳蜗核神经细胞肿胀、胞核皱缩或碎裂、尼氏体减少,以14、30天时改变明显。对照组耳蜗核Caspase3免疫组化染色的灰度值为172.33±17.81,实验组60 Coγ射线照射后1、4、7、14、30d耳蜗核Caspase3免疫组化灰度值分别为136.37±24.42、94.67±15.33、91.40±11.71、110.80±4.23、123.56±32.56,两组比较差异有统计学意义(P<0.05)。结论 60 Coγ射线照射可导致耳蜗核损伤;Caspase3表达上调可能与耳蜗核神经元射线损伤有关。

Objective To study the effects of 60Coγrays irradiation on cochlear nucleus neurons. Methods Forty eight guinea pigs were randomly divided into control group（8 guinea pigs）and experimental group（40 guinea pigs）.The experimental group animals were tested with the auditory brainstem response at 1,4,7,14 and 30 days after irradiation of 40 Gy,then the guinea pigs were sacrificed.All cochlear nuclei tissues were made into paraffin sections.Sections were stained with haematoxylin and eosin and Caspase 3 immunohistochemistry for light microscopic examination. Results ABR threshold in the control group was 29.17±1.95 dB SPL.In experimental group,ABR thresholds were 31.88±2.59 dB SPL,35.00±3.17dB SPL,35.83±2.04 dB SPL,39.17±2.05 dB SPL,41.67±2.58 dB SPL after 60Co irradiation 1,4,7,14,30 days groups,respectively.The differences of ABR threshold were statistically significant（P0.05） in 4,7,14,30 days groups.Compared with that of control ABR wave I,II and III latencies as well as I-II、II-III、and I-III interval latencies were prolonged.HE staining showed that the cochlear nucleus neurons were swelling,shrinked or fragmented,and Nissl bodies reduced in the experimental groups at different time points after 60Coγrays irradiation.The Caspase 3 immunohistochemical gray